The sport requires focused persistent and periodised training for each of the three disciplines, as well as combination workouts and general strength conditioning.

[11][13] These multisport events continued to slowly spread and grow in popularity; by 1934, Les Trois Sports was being hosted in the city of La Rochelle, though it consisted of three distinct events, swimming a 200 m (660 ft) channel crossing, a 10 km (6 mi) bike competition around the harbour of La Rochelle and the parc Laleu, and a 1.2 km (0.75 mi) run in the stadium André-Barbeau.

[17] The race was conceived and directed by two members of the San Diego Track Club, Jack Johnstone and Don Shanahan.

[18] Johnstone recalls that he was a part of the '70s jogging craze in America and that after entering a few races, he was not regaining his "mediocre fitness" despite having been a member of the 1957 Collegiate and AAU All-American swim teams.

The following year, after competing in the event for the second time and placing in the top 10, Johnstone desired more of this style of race and with equal emphasis on the swim.

Two notable entrants, Judy and John Collins, four years later founded the event that brought international attention to the new sport: the Hawaii Ironman.

The initial aim was to establish a new premier competition, the European Triathlon, with the goal of being of the same size and prestige to directly compete with that of Hawaii.

[26] In December of that year the national television station France 2 broadcast a program, Voyage au bout de la souffrance (Journey to the End of Suffering) which detailed the events of the Nice Triathlon.

[25] Some fans of traditional sports strongly criticised this new practice, as seven of the entrants were hospitalised due to the swim, as the temperature of the Mediterranean was only 14 °C (57 °F).

The Nice Triathlon was, alongside Hawaii, one of the two important long-distance races each year for both prize money and media attention.

[28] Around the same time, Canadian Les McDonald held talks with Juan Antonio Samaranch, then president of the International Olympic Committee.

After further discussions on the way forward to reach the Olympics, including the refusal to follow the path of the UIPMB and how triathlon should develop both economically and as a sport, the Congress endorsed the creation of the ITU and elected its first executive committee.

[37] International Ultra-Triathlon Association (IUTA) is the official governing body of Ultratriathlon, which involves triathlon in distances longer than an iron-distance race.

[38] Additionally, each nation, generally, has a sanctioning body for triathlon events in their respective country with regard to athletes competing and qualifying for Olympic competition.

[41] This culminated in 2005 when the ITU and USAT asked all national triathlon federations to refuse to continue sanctioning any WTC events.

[47][48] In 2017, the ITU and WTC signed a memorandum of understanding in which the two organisations stated they will:[49] Triathlons longer than full distance are classed as ultra-triathlons.

Athletes will either be provided or briefed on details of the course, rules, and any problems to look out for (road conditions, closures, traffic lights, aid stations).

[59] At a major event, such as an Ironman or a long course championship, triathletes may be required to set up and check-in their bike in the transition area a day or two before the race start, leaving it overnight and under guard.

[60] On the day of the race, before the start of competition, athletes will generally be provided with a bike rack to hold their bicycle and a small section of ground space for shoes, clothing, etc.

Racers enter the transition area, rack their bicycles, and quickly change into running shoes before heading out for the final stage.

In most races, "aid stations" located on the bike and run courses provide water and energy drinks to the athletes as they pass by.

As such, athletes are not allowed to receive assistance from anyone else outside the race, with the exception of race-sanctioned aid volunteers who distribute food and water on the course.

[72] Additionally, triathletes encounter fewer injuries than those who only use running as part of their exercise routine due to the incorporation of low impact swim and bike training.

[62] In non-sanctioned events or in "age group" classes where most racers are simply participating for the enjoyment of the sport instead of vying for official triathlon placing, wetsuits can often be used at other temperatures.

[77] Other rules have been implemented by race organizers regarding both wetsuit thickness as well as the use of "swim skins;" which need to be considered by those participating in future triathlons.

Triathlon bikes use a specialized geometry, including a steep seat-tube angle both to improve aerodynamics and to spare muscle groups needed for running.

At the end of the bike segment, triathletes also often cycle with a higher cadence (revolutions per minute), which serves in part to keep the muscles loose and flexible for running.

The primary distinguishing feature of running in a triathlon is that it occurs after the athlete has already been exercising in two other disciplines for an extended period of time, so many muscles are already tired.

The transition provides a staging area where bicycles, running shoes, hydration and other gear is set up ready to be used during the course of the event.

The Paralympic event originally scheduled a sprint race with athletes competing in six categories according to the nature of their physical impairments.